The utilization of shaft kilns and rotary kilns for the production of limestone is well known. The rotary kiln produces a higher quality limestone but has a high specific consumption of fuel and/or electricity and a high initial investment. Shaft kilns which are known to us produce lime of a low quality yet have a high consumption of fuel and/or electricity. Furthermore, such kilns have a low rate of production and can only use large grain limestone. Introduction of small grain limestone, that is limestone having an average diameter below a particular size, into conventional shaft kilns results in the small grain limestone being burned and the quality of the product suffers further degradation.